It would be impossible to capture the essence of the Smithsonian Museum's new African-American history museum in just one of the more than 3,000 artifacts on display.

Do you nominate the slave cabin in juxtaposition with the freedman's cabin a floor above it in a space that is like a subterranean cathedral? Do you pick Chuck Berry's cherry-red Cadillac El Dorado, or is it simply more pleasing than resonant?

As an emblem of the story the museum is trying to tell, of a people's journey upward and of the way the African-American story has shaped the American story, you might well select the mural-sized photograph of Barack Obama standing with his wife and daughters in front of tens of thousands of fellow citizens as he officially becomes president of the United States.

Or you could pick an item that helps make the swearing-in image so potent, the slave shackles from about 1845, donated by Oprah Winfrey. On display next to a rough-wood baby's crib from about the same time period — both items tell of brutality and heartbreak, and also reference a modern woman deemed so significant to the culture that her daytime talk show gets its own display in the museum's main, historical exhibition, the one telling the African-American story from arrival to Obama and beyond.

Really, though, the Smithsonian's National Museum of African American History and Culture, located hard by the Washington Monument on the National Mall in a line with other Smithsonian museums, is itself the great symbolic object.

Officially opening Sept. 24 with a public festival and a celebrity-studded celebration, but open Wednesday to some 500 members of the press as a work in progress, the museum is the culmination of decades of "fitful and frustrated efforts," in the words of founding director Lonnie Bunch.

"It was important to us to finish this museum and open it during the time of President Obama," Bunch said Wednesday, seated in a quiet nook near the freedman's cabin, not far from where a plane flown by the famed Tuskegee Airmen hangs overhead.

"I'm humbled by the excitement this has generated," he said. "More than anything else, that's allowing me to smile but also to feel the weight of history."

Take a tour through the Smithsonian Museum's new African-American history museum. (WGN-TV)

Take a tour through the Smithsonian Museum's new African-American history museum. (WGN-TV)

Bunch, 63, was recruited for the job directly from the Chicago Historical Society, now the Chicago History Museum, which he ran for five years until 2005. Since then he has been building a collection, building support, with some $315 million in private funding, and finally building and then furnishing a building.

During that process, he heard from a lot of people with conflicting views, illustration of some of the reasons it took so long to get a national African-American history museum going. Some people wanted him to make a "holocaust museum," Bunch said, and he also heard from those who wanted him to stay away from the harrowing stories.

"I thought that tension between those poles was where we needed to be," he said. "We tell stories of a black middle class growing. We obviously wanted to tell the story of Emmett Till."

In a setting almost like a funeral home visitation, the museum has the coffin of Emmett Till, the Chicago teen who was murdered in 1955 in Mississippi, allegedly for looking at a white woman, and whose death was one of the spurs for the civil rights movement. That section, however, was not accessible Wednesday due to ongoing work on the exhibits.

Some of the toughest material, photographs of lynching, for instance, is set up so that visitors have to be looking straight at it to really view it. But it is not hidden. "At some point racial violence is something everybody has to see," Bunch said.

Jim Lo Scalzo / EPA

An exhibit on the inauguration of President Barack Obama, shown on display at The National Museum of African American History and Culture during a media preview in Washington, D.C. The 400,000-square-foot museum is a Smithsonian Institution museum and will open its doors to the public on Sept. 24.

An exhibit on the inauguration of President Barack Obama, shown on display at The National Museum of African American History and Culture during a media preview in Washington, D.C. The 400,000-square-foot museum is a Smithsonian Institution museum and will open its doors to the public on Sept. 24.

(Jim Lo Scalzo / EPA)

The building is brown in the evening, bronze in sunlight, stolid-seeming from a distance and a great earthy contrast to all the neoclassical wedding-cake architecture elsewhere on the mall. But upward-slanting filigreed metal exterior walls and strategic windows render it surprisingly airy from up close and from the inside.

The design is by architect David Adjaye, the London-based son of a Ghanaian diplomat whose work was celebrated in a 2015 retrospective at the Art Institute of Chicago. The museum building was inspired, he said Wednesday, by a centuries-old African sculpture, a sort of totem, that was part of the Art Institute show and is now in the new museum's gallery celebrating culture.

"This building is for me a new way of looking at creating these narrative museums," Adjaye said. "These stories and the need for them come about as we live together and try and understand each other."

The basic structure of the museum was his idea, he said, the pathway from the beginnings of slavery up to the present. "You go deep into a crypt experience, a very difficult part of history, and then you rise," he said.

After the historical exhibit telling the African-American story, which is all deeply below ground level, visitors find a lower level with a cafe and performance space, the Oprah Winfrey Theater. The ground floor is largely open, welcoming space (and museum shop), the second floor devoted to education. Exhibits resume on the third and fourth floors, where the expansive galleries celebrate community and culture, respectively. The fifth floor is for museum offices.

Zbigniew Bzdak / Chicago Tribune

Lonnie Bunch, director of the Smithsonian Institution's National Museum of African American History photographed in Chicago

Lonnie Bunch, director of the Smithsonian Institution's National Museum of African American History photographed in Chicago (Zbigniew Bzdak / Chicago Tribune)

It is on four, in the culture space, where you'll find Berry's Cadillac, for instance, Bo Diddley's rectangular guitar and a 360-degree, sharply edited video showcasing sharp moments in black culture, from a Maya Angelou reading to a Michael Jordan dunk in progress to Obama dropping the mic and saying "Obama Out."

Floor three tells stories of community, for better and sometimes worse. One section looks at Martha's Vineyard as an African-American vacation haven, an adjacent one at the race riots in Tulsa, Okla., in the early 20th century.

And even within the slavery galleries — the largest gallery space in all of the Smithsonian's collection of museums, Bunch said — there is a balance. "We do punch hard with the harsh realities of slavery, but we also punch hard with the resistance, the resilience and the survival of a people," said Mary Elliot, a curator who worked on that part of the museum's narrative. "That's important for everybody to know. … You learn about the inhumanity of the Middle Passage, but you learn about people who held on to their humanity in the midst of all of that."

The symbolic value of some of the biggest objects the museum displays, some of which had to be lowered in by crane before walls were put around them, are evident: a 20th-century train car standing for long-distance, often-segregated travel, for the Pullman porters (who get a display) and for the Great Migration; a guard tower from Louisiana's notorious Angola Prison symbolizing post-Reconstruction oppression and incarceration and looking menacing even as a historical artifact.

Chip Somodevilla / Getty Images

A pair of slave shackles are on display in the Slavery and Freedom Gallery in the Smithsonian's National Museum of African American History and Culture during the press preview on the National Mall Sept. 14, 2016.

A pair of slave shackles are on display in the Slavery and Freedom Gallery in the Smithsonian's National Museum of African American History and Culture during the press preview on the National Mall Sept. 14, 2016.

(Chip Somodevilla / Getty Images)

And what does the spaceship from Parliament-Funkadelic's riotous 1970s stage shows bring to the party? The funk, obviously.

For all the fundamental sobriety here, deft touches abound, beginning with Adjaye's angled cutaway window framing the Washington Monument. In the slavery section, viewers travel a tight dark hall and then come into the big, multi-story "cathedral space," where they learn of the Declaration of Independence, more idealistic on paper than the nation would be in practice; then more tight halls follow and the next time you hit the open space, the Civil War has ended.

Even the big cafeteria is cleverly adorned, with museum displays related to food on the walls: the Rev. Martin Luther King Jr. pictured at a meal with his family, a Langston Hughes quote about being sent "to eat in the kitchen when company comes, / But I laugh and eat well, and grow strong."

The museum is free to the public, like all the Washington Smithsonian museums, but for the foreseeable future, officials said, high demand means timed-entry passes must be reserved ahead of time. Only a limited number will be available on the day of visit.

Susan Walsh / AP

A statue of Chicago Bulls basketball great, hall-of-famer Michael Jordan is featured at the National Museum of African American History and Culture in Washington, Wednesday, Sept. 14, 2016.

A statue of Chicago Bulls basketball great, hall-of-famer Michael Jordan is featured at the National Museum of African American History and Culture in Washington, Wednesday, Sept. 14, 2016.